JP7300245B2 - SOLAR CELL, SOLAR MODULE AND MANUFACTURING METHOD THEREOF - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solar cell, a solar cell module, and a method of manufacturing the same, in which the shape of the electrode is improved so that the solar cell can be easily modularized and the cost can be reduced.
[Related Application]
This application is a priority application under the Paris Convention based on Korean Patent Application No. 10-2017-0075019. The matters disclosed in the original specification, drawings, etc. of the Korean patent application constitute the content of the present invention, and these matters are included as the disclosure content of this specification.

A general solar cell includes semiconductor portions that form a pn junction with different conductive types, such as p-type and n-type, and electrodes that are connected to the semiconductor portions of different conductive types. Prepared and made. A solar cell having such a configuration generates electric power using a solar cell module made by connecting a plurality of solar cells.

As one method for improving the power generation efficiency of solar cells, a standardized solar cell, for example, one solar cell made from a wafer is divided into multiple pieces to make cut cells, and these cut cells are partially overlapped to generate electricity. A physically connected supercell was proposed.

The reason why the solar cell module is configured with cut cells in this way is that the output loss can be reduced. The output loss has the value of the square of the current in the solar cell multiplied by the resistance. The current also increases, and the smaller the area of the solar cell, the smaller the current. Therefore, the smaller the area of the solar cell, the smaller the power loss.

A plurality of cut cells are partially overlapped in an overlapping region and bonded with a conductive adhesive to form a series-connected module.

For this reason, in general, a bus bar or a pad formed separately from the bus bars or electrodes that connect the finger electrodes respectively arranged on the front and back sides of the cut cells is arranged in the overlapping region, and the bus bars or electrodes of the adjacent two cut cells are arranged. Pads are connected via conductive adhesive, solder, or the like.

However, such a conventional method has the problem of increasing manufacturing time and cost because the busbars or pads must be formed separately from the electrodes.

In addition, such a conventional method necessarily requires an alignment process in which the pads or bus bars must be aligned when connecting the cut cells to each other, which also increases manufacturing time and costs. .

The present invention was created in view of such technical background, and an object of the present invention is to facilitate solar cells, easily modularize them, and reduce manufacturing costs.

The present invention aims to solve various other technical problems, but the problems not described here will be explained together with the explanation of the present invention, or otherwise can be easily predicted through the description of the present invention.

One aspect of the present invention is as follows.
[1] A solar cell,
a semiconductor substrate having a short side in a first direction and a long side in a second direction intersecting the first direction;
comprising a plurality of electrodes formed on one surface of the semiconductor substrate and physically separated from those adjacent in the second direction;
The solar cell, wherein the plurality of electrodes comprises junctions comprising a conductive material that physically or electrically connects the plurality of electrodes adjacent in the second direction.
[2] The solar cell according to [1], wherein the junction is positioned at one end of the plurality of electrodes near the long side.
[3] The solar cell according to [1] or [2], wherein the area where the plurality of electrodes are formed is 5% or less of the area of the entire one surface of the semiconductor substrate.
[4] The plurality of electrodes according to any one of [1] to [3], wherein the plurality of electrodes are arranged apart from the long side by 200 (μm) to 300 (μm) in the first direction. A solar cell as described.
[5] the number of the plurality of electrodes is 80 to 120;
The solar cell according to any one of [1] to [4], wherein the distance between the plurality of electrodes in the second direction is 1 to 2 (mm).
[6] The solar cell according to [5], wherein the distance between the plurality of electrodes adjacent in the second direction is constant.
[7] in the plurality of electrodes, the distance between two electrodes adjacent in the second direction gradually decreases,
[1] to [6], wherein the joints of the two electrodes adjacent in the second direction are arranged such that the distance between the joints adjacent in the second direction is the minimum. The solar cell according to any one of the items.
[8] further comprising a bussing portion for physically connecting two electrodes adjacent in the second direction among the plurality of electrodes,
The solar cell according to [5], wherein the bushing portion is located near another long side far from the joint portion.
[9] The joint portion according to any one of [1] to [8], wherein the aspect ratio (length in the second direction/length in the first direction) is 1/26 to 3/10. solar cells.
[10] The plurality of electrodes are formed to extend in the first direction at the joint,
further comprising a finger portion having a line width smaller than the line width of the joint portion in the second direction;
The solar cell according to [9], wherein the junction further comprises an open pattern that partially exposes the semiconductor substrate.
[11] The solar cell according to any one of [1] to [10], wherein in the plurality of electrodes, the unit area of the junction is larger than the unit area of the portion excluding the junction. .
[12] A solar cell module comprising:
a semiconductor substrate having a short side in a first direction and a long side in a second direction intersecting the first direction;
a first electrode disposed on the first surface of the semiconductor substrate;
a second electrode disposed on the second surface of the semiconductor substrate;
a plurality of solar cells partially overlapping adjacent solar cells along the long side and including an overlapping region arranged on the long side;
In the plurality of solar cells, the second electrode located on the second surface of the first solar cell and the first electrode located on the first surface of the second solar cell adjacent to each other have the conductivity imparted to the overlapping region. directly connected electrically and/or physically by an adhesive,
the first electrodes are arranged physically separate and parallel to adjacent ones in the second direction and/or comprise junctions arranged in the overlapping region;
The solar cell module, wherein the conductive adhesive is configured to electrically connect between the first electrodes in the second direction.
[13] The solar cell module according to [12], wherein in the first electrode, the unit area of the joint is larger than the unit area of the portion excluding the joint.
[14] According to [12] or [13], the junction of the first electrode formed on the second solar cell is hidden by the first solar cell so as not to be seen visually. solar modules.
[15] A method for manufacturing a solar cell module, comprising:
The solar cell module comprises a first solar cell and a second solar cell having a short side in a first direction and a long side in a second direction intersecting the first direction,
applying a conductive adhesive to the second solar cell having a plurality of electrodes formed at one end and arranged parallel in a second direction;
positioning the first solar cell so as to overlap the second solar cell in the overlap region where the conductive adhesive is applied; and curing the conductive adhesive to form the first solar cell; physically and/or electrically connecting said second solar cell;
the junction is arranged in an overlap region where the first solar cell and the second solar cell are overlapped;
The method of manufacturing a solar cell module, wherein the conductive adhesive is constructed such that the plurality of electrodes spaced apart in the second direction are connected to joints of adjacent electrodes in the overlapping region. .
In the embodiment of the present invention, a semiconductor substrate having a short side in a first direction and a long side in a second direction intersecting the first direction, and formed on one surface of the semiconductor substrate, a plurality of electrodes physically spaced apart from adjacent ones in two directions, said plurality of electrodes being a conductive material physically and electrically connecting said plurality of electrodes adjacent in said second direction. A solar cell is disclosed that includes a junction provided with

The junction may be located at one end of the plurality of electrodes near the long side.

The area where the plurality of electrodes are formed may be formed to occupy 5% or less of the area of the entire surface of the semiconductor substrate.

The plurality of electrodes may be arranged apart from each of the long sides by 200 (μm) to 300 (μm) in the first direction.

The number of the plurality of electrodes may be 80-120, and the distance between the plurality of electrodes in the second direction may be 1-2 (mm). Further, the distance between the plurality of electrodes adjacent in the second direction can be constant.

Among the plurality of electrodes, the distance between two electrodes adjacent in the second direction is gradually reduced, and the joints of the two electrodes adjacent in the second direction are the joints adjacent in the second direction. can be arranged such that the distance between

The maximum line width of the plurality of electrodes may be 3 to 5 times the minimum line width ratio.

Each of the plurality of electrodes may have a needle shape with a line width gradually decreasing in the first direction.

Further comprising a bushing portion physically connecting two electrodes adjacent in the second direction among the plurality of electrodes, wherein the bushing portion may be located near another long side far from the joint portion. can.

The joint may have an aspect ratio (length in the second direction/length in the first direction) of 1/26 to 3/10.

The plurality of electrodes may further include finger portions extending in a first direction from the junction and having a line width smaller than a line width of the junction in the second direction.

The junction may further include an open pattern partially exposing the semiconductor substrate.

In the plurality of electrodes, the unit area of the joint may be larger than the unit area of the portion excluding the joint.

In another embodiment of the present invention, a semiconductor substrate having a short side in a first direction and a long side in a second direction intersecting the first direction; an electrode, a second electrode disposed on the second surface of the semiconductor substrate, and a plurality of solar cells partially overlapping adjacent solar cells along the long side and including an overlapping region disposed on the long side; wherein a second electrode located on the second surface of the first solar cell and a first electrode located on the first surface of the second solar cell adjacent among the plurality of solar cells are provided in the overlap region. Directly and electrically physically connected by a conductive adhesive, the first electrodes are arranged so as to be physically separated and parallel to adjacent ones in the second direction, and arranged in the overlap region. and wherein said conductive adhesive is provided to electrically connect between said first electrodes in said second direction.

The conductive adhesive may be provided over the overlap area.

In the first electrode, the unit area of the joint may be larger than the unit area of the portion excluding the joint. The junction of the first electrode formed on the second solar cell is visually blocked by the first solar cell.

In another embodiment of the present invention, a method for manufacturing a solar cell module including first and second solar cells each having a short side in a first direction and a long side in a second direction intersecting the first direction. providing a conductive adhesive to a second solar cell having a plurality of electrodes arranged parallel in a second direction and having a joint formed at one end; positioning a first solar cell to overlap with the second solar cell in a provided overlap region; and curing the conductive adhesive to physically attach the first solar cell and the second solar cell. , electrically connecting, wherein the joint is disposed in an overlap region where the first solar cell and the second solar cell are overlapped, and the conductive adhesive is applied to the overlap region in the overlap region; A method of manufacturing a solar cell module is disclosed wherein the plurality of electrodes spaced apart in a second direction are provided to be connected to junctions of adjacent electrodes.

The conductive adhesive may be provided over the overlap area.

According to an embodiment of the present invention, when a portion of the solar cell is stacked to form a module, physically separated electrodes formed on one surface of the solar cell using a conductive adhesive can be connected to each other. By mechanically joining two adjacent solar cells while making an electrical connection, manufacturing costs and time can be reduced.

FIG. 2 is a diagram showing a schematic planar shape of a solar cell module made of cut cells; FIG. 2 is a diagram showing the shape of a cross section taken along line A-A' in FIG. 1; FIG. 4 is a schematic diagram briefly explaining the process of making a cut cell from a mother cell; FIG. 4 is a schematic diagram briefly explaining the process of making a cut cell from a mother cell; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; FIG. 2 shows solar cells with electrodes of various shapes; 4 is a flow chart illustrating a method for manufacturing a solar cell module according to one embodiment of the present invention; It is a figure which illustrates the mask pattern used when producing a needle-like electrode. It is a figure which illustrates S11 and S13 steps typically. FIG. 21 is a diagram showing a cross-sectional shape taken along line B-B' of FIG. 20;

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that those skilled in the art can easily carry them out.

This invention may, however, be embodied in many different forms and is not limited to the embodiments set forth herein. In addition, in order to clearly explain the present invention with the drawings, parts that are not related to the explanation may be simplified or omitted. In addition, the various embodiments shown in the drawings are presented as examples, and for convenience of explanation, they may not be shown to scale, and the shapes and structures are also simple. It may be shown in a modified form.

FIG. 1 is a schematic plan view of a solar cell module according to an embodiment of the present invention, and FIG. 2 shows a cross-sectional shape taken along line A-A' in FIG.

Referring to FIGS. 1 and 2, in one embodiment of the present invention, a plurality of solar cells are positioned so as to partially overlap adjacent ones and provide a conducting region 100 in the overlapping overlap region 100 . They are electrically and mechanically connected and joined by an adhesive (not shown) to form a string (ST).

In one preferred form, the solar cell 10 can be configured to include a plurality of electrodes 13 positioned on the front side and arranged to face in one direction (the x-axis direction in the figure). In one example, the plurality of electrodes 13 formed on the front surface are arranged so as to be separated from adjacent ones in the second direction (y-axis direction in the figure), and in the first direction (x-axis direction in the figure): It can be arranged so as to be positioned on the same line as the electrodes of other adjacent solar cells. As a result, when a plurality of solar cells are stacked in the overlapping region 100, the electrodes 13 appear to be formed of one electrode in the first direction (the x-axis direction in the figure), improving the design. can be done.

Adjacent first and second solar cells (10a, 10b) are not only electrically and mechanically connected and joined by the conductive adhesive provided in the overlapping area 100, but also placed on the solar cells. The electrodes 13 are electrically connected. Here, the conductive adhesive is formed as an organic/polymer matrix and a metal filler, the metal filler providing electrical properties, and the polymer matrix providing physical and mechanical properties. It is used in a generic sense.

A portion of first solar cell 10a is arranged on the front surface of second solar cell 10b from overlapping region 100, and a portion of the rear surface of first solar cell 10a and the front surface of second solar cell 10b from overlapping region 100 are separated from each other. Some overlap. As a result, the electrode arranged on the back surface of the first solar cell 10a and the electrode arranged on the front surface of the second solar cell 10b face each other from the overlap region 100, and the conductive adhesion provided in the overlap region 100 can be electrically connected by an agent. Thereby, the first solar cell 10a and the second solar cell 10b can be electrically connected in series and also mechanically joined to the overlap region 100 by a conductive adhesive.

Preferably, the width of the overlapping region 100 (in the x-axis direction in the figure) is 1/20 to 1 of the width of the solar cell 10 (in the x-axis direction in the figure) when considering the adhesive strength of the conductive adhesive. It can have a size of /15. If the width of the overlapped region is less than 1/20, the overlapped region is too small and it is difficult to obtain sufficient mechanical bonding strength. There is a problem that is lower than expected. Considering this point, in one example of the present invention, the width of the overlapping region can be 1 to 2.5 (mm).

As shown in FIG. 2, the strings (ST) can be formed into modules by being laminated between the front transparent substrate 10 and the back sheet 40 .

As an example, the strings (ST) are placed between the front transparent substrate 30 and the back sheet 40, and the transparent filler 20, such as a polymer sheet (e.g. EVA), is placed on the front and back of the strings (ST). In the assembled state, they can be consolidated and encapsulated by a lamination process in which heat and pressure are applied simultaneously.

Here, the front transparent substrate 10 may be made of tempered glass or the like, which has a high transmittance and an excellent breakage prevention function.

The back sheet 40 can prevent permeation of moisture from the back of the strings (ST) to protect the solar cells from the external environment. Such a backsheet 40 may have a multi-layer structure such as a layer for preventing permeation of moisture and oxygen, a layer for preventing chemical corrosion.

The rear sheet 40 is a thin sheet made of insulating material such as FP (fluoropolymer) or PE (polyester), but may be an insulating sheet made of other insulating material.

In a preferred embodiment, the lamination process may be performed with the sheet-shaped filler 20 placed between the front transparent substrate 30 and the strings (ST) and between the strings (ST) and the back sheet 40. can.

Here, the material of the filler 20 is ethylene vinyl acetate (EVA), which can prevent corrosion due to permeation of moisture, protect the string (ST) from impact, and thus absorb impact. can be made of any material.

The solar cells that constitute the solar cell module described above can be realized by cut cells. As shown in FIGS. 3 and 4, the cut cell 10 can be produced by dividing a standardized solar cell (hereinafter referred to as a mother cell) 1 made from a wafer into a plurality of cells. However, in the figure, it is exemplified that one mother cell is divided into six to create six cut cells 10 .

The mother cell 1 can be configured including a plurality of divided electrodes 13 so as to facilitate division of the solar cell. As shown, the electrodes 13 are separated into multiple pieces based on the scribing line (SL) for easy removal along the scribing line (SL). As shown, mother cell 1 is divided into six cut cells 10, so electrode 16 is also divided into six along its length.

Moreover, it is desirable that the electrodes 13 are positioned on the same line in the length direction (the x-axis direction in the drawing). According to this, even when the mother cell 1 is divided into a plurality of cut cells 10, the electrodes arranged in each cut cell 10 can be arranged in the same shape and at the same position, and henceforth, the cut cells It is easy to align the electrodes when arranging the electrodes 10 on top of each other.

On the other hand, the electrodes arranged in the mother cell 1 are elongated only in the longitudinal direction as shown. Because the electrodes have such a simple shape, the manufacturing process for forming the electrodes can be simplified to reduce manufacturing costs. In addition, even when the mother cell 1 is divided into a plurality of cut cells 10 and these are stacked, the electrodes arranged in each cut cell are arranged on the same line in the length direction. Easy to place.

In terms of design, since the shape of the electrode arrangement of the mother cell 10 is substantially the same as the shape of the electrode arrangement of the module made of cut cells, there is no gap between the module made of cut cells and the mother cell. It has the advantage of reducing design differences.

Preferably, the mother cell 1 is divided into 3 to 12 cells. If the mother cell 1 is divided into less than 3 cells, it is difficult to effectively reduce the output loss. output may decrease over time.

Since the cut cell is made by dividing the mother cell 1 in this way, unlike the mother cell 1, it has a rectangular shape with short sides and long sides, and the aspect ratio (length of the short side/length of the long side) is length) is determined by the number of divisions, preferably 1/3 to 1/12. When the aspect ratio had a value within such a range, when the cut cell was modularized, a sufficient overlapping region was secured and sufficient mechanical bonding strength required could be obtained.

The mother cell 1 has already been configured including all necessary components for electric power generation, such as a semiconductor substrate forming a pn junction, a back surface electric field portion, a passivation film, and an electrode for collecting charges. , omitted for convenience of explanation. This mother cell 1 can be, without any particular limitation, various types of solar cells that have been developed up to now, such as heterojunction solar cells, bifacial solar cells, and back contact solar cells. of solar cells can all be used. A mother cell 1 may be divided by irradiating a laser along a scribing line (SL).

The laser (LA) is preferably applied to the surface of the mother cell 1 opposite to the light-receiving surface that receives the light. When the mother cell 1 is irradiated with the laser, the dividing grooves are formed while the surface of the solar cell is melted and cooled by the laser. At this time, due to the high heat of the laser, the surroundings of the dividing grooves receive heat energy together, and the bonds between silicon (Si) that have been stabilized in this process are broken. Since the number of recombination sites increases, it is desirable that the surface opposite to the light-receiving surface of the mother cell 1 is irradiated with the laser when the solar cell is irradiated with the laser.

Also, the laser (LA) is desirably irradiated outside the region forming the pn junction. As is well known, solar cell 1 produces electricity through a pn junction between a semiconductor substrate and an emitter. By the way, if the region in which the emitter is formed is irradiated with a laser, the pn junction region is destroyed by the laser, so that the power generation efficiency of the solar cell is reduced.

As an example, in a solar cell having a general structure in which the emitter is formed on the front surface of the solar cell 1 and the electrodes are separately formed on the front surface and the back surface of the solar cell in accordance with this, the laser is applied to the solar cell in which the emitter is not formed. The back of the can be irradiated.

Then, in a back contact solar cell in which the emitter and the back surface field field (BSF) are all formed on the back surface of the semiconductor substrate, the laser is irradiated on the back surface opposite to the light receiving surface, but the emitter is formed on the back surface. A region can be irradiated to escape.

In this manner, the laser is applied to a position outside the pn junction where carriers are generated, thereby preventing the power generation efficiency of the solar cell from being reduced.

By irradiating the laser along the scribing line (SL), dividing grooves (SH) are formed along the scribing line (SL) in the surface 1a of the mother cell 1 irradiated with the laser (LA). be done. Here, the scribing line (SL) is an imaginary line indicating the direction in which the solar cell is irradiated with the laser in order to divide the mother cell 1 . A pulsed laser can be used to desirably reduce laser damage. Since the pulse-type laser irradiates the laser in synchronization with the pulse, it is not irradiated continuously while the laser scans the mother cell 1, but is irradiated intermittently, so the laser is continuously irradiated. It can reduce thermal damage to the solar cell compared to linear lasers. Also, the laser (LA) is preferably irradiated several times along each scribing line (SL) rather than once to form the dividing groove (SH). , the number of times of irradiation can be adjusted by considering the intensity of the laser, the depth (D1) of the division groove (SH), and the like. According to this, it is possible to irradiate the laser with a reduced intensity of the laser, and effectively reduce damage to the solar cell during the scribing process.

The depth (D1) of the dividing groove (SH) is preferably 50% to 70% of the thickness (T1) of the mother cell 1. FIG. After the dividing grooves (SH) are formed, the mother cell 1 is subjected to physical force and divided into a plurality of cut cells 10 . Now, when the depth (D1) of the dividing groove (SH) is less than 50%, the mother cell 10 cannot be divided along the dividing groove (SH), and defects such as cracks may occur in the mother cell 1. can. When the depth (D1) of the dividing groove (SH) is 70% or more, the thermal stress transmitted to the mother cell 1 increases and the efficiency of the cut cell 10 can be lowered.

Hereinafter, solar cells having electrodes of various shapes will be described in detail according to embodiments with reference to the accompanying drawings.

FIG. 5 shows a planar shape of a solar cell according to one embodiment of the present invention. In one preferred form, the solar cell 10 comprises a semiconductor substrate forming a pn junction, and first and second electrodes respectively formed on the first and second surfaces of the semiconductor substrate. can be done. Here, for example, the first surface may be a surface for receiving light, and the first electrode may be located thereon, and the rear surface may be a surface opposite to the front surface, where the second electrode may be located.

On the other hand, in the following embodiments, among the first electrode and the second electrode, various embodiments will be described by taking the first electrode as an example, but the present invention is not limited to this. , the first electrode or the second electrode, or all may have the same shape as the first electrode described below.

The semiconductor substrate 11 can have a short side (11a) in the first direction (x-axis direction in the figure) and a long side 11b in the second direction (y-axis direction in the figure). In one preferred form, the aspect ratio of the semiconductor substrate 11 can be from 3/1 to 1/12.

The first electrodes 13 are positioned on the front surface of the semiconductor substrate 11 and may be formed in a stripe arrangement physically separated from adjacent ones in the second direction. The first electrode 13 is preferably formed to occupy less than 5% of the front surface area of the semiconductor substrate 11 so as not to block light incident on the front surface as much as possible. If the area where the first electrode 13 is formed is 5% or more, the light receiving area is reduced due to the first electrode 13, and not only does the desired output not come out, but also the manufacturing cost rises, resulting in price competitiveness. may decrease.

More preferably, the area where the first electrode 13 is formed is 3% or less of the front surface area of the semiconductor substrate 11 .

In an embodiment, the first electrode 13 is formed to have a structure without a bus electrode unlike the prior art. In the art, a first or second electrode comprises a plurality of finger electrodes that collect charge and a bus electrode that connects the finger electrodes to each other and to ribbons that connect between the solar cells. was common. Now, since the bus electrode must be connected to the ribbon, it is formed to have a line width larger than that of the finger electrode, resulting in increased manufacturing cost and reduced light receiving area.

In the embodiment of the present invention, in consideration of such points, the first electrode 13 arranged on the front surface is not formed with the bus electrode, but the joint portion 13a is formed as a part of the first electrode 13. is configured to have

The joints 13a are provided with a conductive adhesive material for electrical and mechanical connection when the solar cells 10 are stringed with the long sides 11b overlapping adjacent ones, and the second adjacent in the second direction. 1 electrode 13 can be electrically connected.

In one preferred form, the joints 13a are formed as part of the first electrodes 13 and can be formed individually for each first electrode 13 . In the embodiment of FIG. 5, the joint portion 13a may be partially constituted by the joint portion 13a including the end portion (13a1) of the first electrode 13 adjacent to the long side 11b. Also, it is desirable that the unit area of the joint portion 13a is larger than the unit area of the first electrode 13 excluding the joint portion 13a. Here, the unit area means the area where the electrode is formed in a fixed area, and for example, it can mean the area where the electrode is formed per 1 (mm 2 ).

In FIG. 5, the first electrode 13 including the joint portion 13a may be formed to have a needle shape with a sharp tip whose line width gradually decreases in the first direction. The joint 13a formed as part of the end (13a1) of the first electrode 13 has a relatively larger unit area than other parts, and accordingly, when the solar cells are positioned to overlap each other around the joint, The electrodes of two overlapping solar cells can be joined with sufficient area. Therefore, the electrodes of the two solar cells can be connected to each other without using pads or bus electrodes as in the conventional art.

In this embodiment, since the first electrode 13 has a needle shape with a gradually decreasing line width, the area where the first electrode 13 is formed is configured to be 5% or less of the front surface of the semiconductor substrate, that is, the light receiving surface. can do.

As one preferred form, for example, when dividing a mother cell of M4 size (161.7 (mm) × 161.7 (mm)) used in an industrial site into six, the number of first electrodes 13 is 80. It is preferable that the number of the first electrodes 13 is less than 120. At this time, the interval (or pitch) (D2) between the first electrodes 13 is preferably about 1 (mm) to 2.0 (mm). . If the distance between the first electrodes 13 is less than 1 (mm), the distance between the electrodes is too dense, and the shadow effect reduces the power generation efficiency and increases the manufacturing cost, resulting in price competitiveness. can be reduced. When the distance between the first electrodes 13 is greater than 2.0 (mm), the distance between the electrodes is too wide, making it difficult to collect charges generated by light. Moreover, it is desirable that the end portion (13a1) of the first electrode 13 be arranged apart from the long side 11b by 200 (μm) to 300 (μm). As described above, a solar cell formed by dividing a mother cell is divided into a plurality of cut cells through a laser scribing process. At this time, considering the resolution of the laser and the working margin, it is preferable that the first electrode 13 be formed apart from the long side 11b by 200 (.mu.m) to 300 (.mu.m).

In a preferred form, the end (13a1) of the first electrode 13, that is, the maximum line width is preferably 120 (μm) to 200 (μm). As described above, the end portion (13a1) forms the joint portion 13a. Therefore, in order to secure the minimum joint area, the end portion (13a1) must be 120 (μm) or more. If it is larger than (μm), the area where the first electrode 13 is formed becomes excessively large, which causes a problem of increased manufacturing cost.

Moreover, it is desirable that the minimum line width of the first electrode 13 is 40 (μm). If the minimum line width of the first electrode 13 is less than 40 ([mu]m), a curl phenomenon may occur in which the tip of the electrode is rolled up during the process of printing and baking the electrode.

Considering these points, it is preferable that the maximum line width of the first electrode 13 is three to five times as large as the minimum line width of the first electrode.

On the other hand, when the first electrodes 13 are formed to have a needle shape, the distance between the first electrodes 13 gradually widens in the second direction (the y-axis direction in the drawing). For this reason, it may be difficult for the charge produced in this part to be normally collected in the first electrode (13a1). In consideration of this point, as illustrated in FIG. 6, it is possible to further include a berthin portion 15 connecting between the first electrodes 13 . The versin portion 15 can be arranged so as to be closer to the right long side 11b' facing the left long side 11b than to the left long side 11b.

In a preferred embodiment, the line width of the berthine part 15 is preferably about 50 (μm) in consideration of the manufacturing process, the manufacturing cost, and the area where the first electrode 13 is formed on the front surface.

In addition, the varsine portion 15 can be formed smaller than the average line width of the first electrode as compared with the first electrode 13. If the line width of the versin portion 15 is larger than the average line width of the first electrode, It is difficult to form the first electrode 13 to have an area of 5% or less. Here, the average line width means the average value of the maximum line width and the minimum line width of the first electrode.

As illustrated in FIG. 6, the versin portion 15 extends parallel to the right long side (11b') from the direction (y-axis direction in the drawing) intersecting the extending direction (x-axis direction in the drawing) of the first electrode 13. and is connected to the entirety of the plurality of first electrodes 13 .

On the other hand, in the embodiment of FIG. 6, the description has been given assuming that the entirety of the plurality of first electrodes 13 are connected by the berthin portion 15, but it is not necessarily formed in this manner. Considering the manufacturing cost and the light receiving area, the versin portion 15 can be partially formed as illustrated in FIG. According to FIG. 7, the versin portion 15 is arranged to connect only two first electrodes 13 that are adjacent in the second direction (the y-axis direction in the figure), but the light receiving The berthin part 15 can be formed considering the correlation between the area and the manufacturing cost.

Please refer to FIG. 8 below. In this embodiment, the first electrodes 13 can be formed in a stripe arrangement physically separated from the second direction (the y-axis direction in the drawing).

In addition, each of the first electrodes 13 may include a finger portion 13b extending in the first direction (the x-axis direction in the figure) from the joint portion 13a to the joint portion 13a adjacent to the long side 11b. can.

The joint 13a can have a rectangular shape, with a width (x-axis direction in the drawing) of 0.5 (mm) to 1.3 mm and a length (y-axis direction in the drawing) of 50 (μm) to 1.3 mm. It can be formed to have a larger value than the finger portion 13b within 150 (μm). Therefore, the joint portion 13a may have an aspect ratio (vertical/horizontal) of 1/26 to 3/10. If the aspect ratio of the joint 13a is less than 1/26, the joint 13a becomes too thin, and it is difficult to secure a sufficient joint area when connecting the first and second solar cells. If the aspect ratio of 13a is greater than 3/10, the joint 13a will be unnecessarily thick, which will only increase the manufacturing cost.

The reason why the joint portion 13a has such a shape that is longer in the horizontal direction than in the vertical direction is that when the first and second solar cells are arranged to overlap each other, the first electrode of the first solar cell is aligned with that of the second solar cell. This is to enable effective contact with the second electrode.

In a preferred form, the first solar cell and the second solar cell are preferably joined by about 1.5 mm. At this time, the second electrode formed on the back surface of the second solar cell may have the same shape as the first electrode, but the joint portion 13a has a shape that is long in the length direction, and the first electrode has the same shape as the first electrode. When the second electrode and the second electrode are overlapped, they can have a sufficient contact area in their length direction (the x-axis direction in the figure), so that when the first electrode and the second electrode are connected, the joint portion can effectively reduce line resistance. The joint part 13a formed in this way increases the area where the conductive adhesive is provided, and when the first electrode 13 is formed by, for example, a screen printing method, heat is easily discharged during the process of baking the paste. It can further include an open pattern 131 that allows the

The open pattern 131 also widens the surface area of the joint 13a to increase the application area of the conductive adhesive when stringing two adjacent solar cells, so that the conductive adhesive is sufficiently applied to the joint 13a. To prevent a viscous conductive adhesive from flowing and spreading.

In one example, the open pattern 131 can be formed with an open space from which a portion of the joint 13a is removed.

Such open patterns 131 can be formed to have various shapes without particular limitation, and various embodiments thereof are illustrated in FIGS. 9-14.

First, referring to FIG. 9, the open pattern 131 may be positioned inside the joint 13a and formed to have a substantially square shape. Thereby, the joint portion 13a has a square shape as a whole.

In comparison, the open pattern 131 exemplified in FIG. 10 is different from the open pattern 131 shown in FIG. 9 in that it is configured to have at least two or more partitioned spaces.

When the open pattern 131 is formed in this way, the conductive adhesive can be confined in the open pattern 131 during the process of applying the conductive adhesive. , a greater bonding force can be obtained.

11 and 12, the open pattern 131 of this embodiment differs from the open pattern of the previous embodiment in that it is formed in an open space. As shown in FIG. 11, the open pattern 131 of this embodiment can be formed to have a horseshoe shape.

The difference is that the open pattern 131 illustrated in FIG. 11 has a left-open shape, and the open pattern 131 illustrated in FIG. 12 has a right-open shape.

Accordingly, although heat and gas may be generated during the process of curing the conductive adhesive provided to the joint 13a, the gas and heat generated during the curing process can be easily discharged.

Referring to FIGS. 13 and 14, the open pattern 131 of this embodiment can be formed to have a shape that is vertically open and left/right closed. The joints 13a having the open pattern 131 having such a shape may be formed to have a shape that is spaced apart and opposed in the first direction (x-axis direction in the figure).

Such an open pattern 131 has the advantage that it is easy to apply a conductive adhesive to the open area. In one embodiment, the conductive adhesive may be elongated in the second direction (the y-axis direction in the drawing), but the open pattern 131 formed in the joint 13a is vertically open. but the left/right are closed. Therefore, the conductive adhesive supplied to the joint portion 13a is guided by the joint portion 13a and the open pattern 131, and is elongated in the second direction so that the conductive adhesive can be applied.

On the other hand, in the above-described embodiment of the open pattern, the open pattern 131 is formed on the square joint portion 13a, but the present invention is not limited to this, and the above-described embodiment can be used. and can be similarly formed on the entire electrodes of the embodiments described below.

FIG. 15 shows a planar shape of a solar cell according to still another embodiment of the present invention.

Referring to FIG. 15, in this embodiment, each of the first electrodes 13 has a joint portion 13a adjacent to the long side 11b and a finger portion extending from the joint portion 13a in the first direction (the x-axis direction in the drawing). 13b.

Here, the finger portion 13b may have a zigzag shape (or wave pattern). When the finger portions 13b are formed to have a zigzag shape in this way, the solar cell in which the aspect ratio of the semiconductor substrate 11 is formed to be 1/3 to 1/12 and the short sides are short, The length of the finger portion 13b formed in the lengthwise direction of the short side can be formed longer than in the case of a straight line.

FIG. 16 shows a planar shape of a solar cell according to still another embodiment of the present invention.

Referring to FIG. 16, in this embodiment the first electrodes 13 are arranged parallel to their neighbors in the second direction. Thereby, the distance between the first electrodes 13 can be constant in the second direction.

In this embodiment, the distance between the first electrodes is 1-2 (mm), the number of the first electrodes 13 can be 80-120, and the line width can be 50-120 (μm). When the line width is less than 50 (μm), the line width of the electrode is too thin and it is difficult to collect charges. may decrease.

The joint portion 13a is configured as a part of the first electrode 13, and preferably, a partial region including the end portion (13a1) of the first electrode 13 can be configured by the joint portion 13a. Preferably, joint 13a is located adjacent to long side 11b.

On the other hand, when two adjacent solar cells are stringed as described above, a conductive adhesive is applied along the long side 11b to electrically connect the first electrodes 13 physically separated in the second direction. be physically connected.

Therefore, even when the joint portion 13a is formed as a part of the first electrode 13 and has a small line width, the conductive adhesive physically and electrically connects the adjacent first electrodes 13, and the connection between the adjacent first electrodes 13 is also possible. The electrodes of the solar cells can also be physically and electrically connected, and two adjacent solar cells can be easily stringed without problems such as alignment.

FIG. 17 shows a planar shape of a solar cell according to still another embodiment of the present invention.

In this embodiment, the first electrode 13 may be configured with a joint size including a first electrode portion 135 and a second electrode portion 137 .

The first electrode part 135 and the second electrode part 137 are arranged parallel to each other in the second direction, and each includes joints (1351, 1371) in one stage. Here, the joints (1351, 1371) are formed adjacent to the same long side 11b.

As shown, the first electrode portion 135 has a needle shape, while the second electrode portion 137 has a straight shape, and the junction 1351 of the first electrode portion 135 is the junction portion of the second electrode portion 137 . It can be configured to have an area greater than 1371.

According to such a configuration, the problems in the case of forming all the first electrode portions 135 and the case of forming only the second electrode portions 137 can be reduced, and the advantages can be enhanced. For example, when the first electrode portion 135 is configured only, the area occupied by the first electrode is larger than when the first electrode portion 137 is configured only. As a result, the manufacturing cost rises and the light receiving surface is reduced, but there is an advantage that a sufficient bonding area can be secured.

In contrast, when only the second electrode part 137 is formed, the area occupied by the first electrode is smaller than when only the first electrode part 135 is formed. can be used, but the bonding area may be reduced.

Therefore, in this embodiment, the first electrode 13 is configured so that the size of the joint portion includes the other first electrode portion 135 and the second electrode portion 137, thereby effectively reducing the joint area and manufacturing cost. to be able to balance

A solar cell module and a method of manufacturing the same according to an embodiment of the present invention will be described below with reference to FIGS. 18 to 21. FIG.

Referring to this figure and the above-described figures, a solar cell module according to an embodiment of the present invention has a short side in a first direction (x-axis direction in the figure) and a short side in a second direction (y-axis direction in the figure). and includes a plurality of solar cells 10 arranged such that the long sides partially overlap each other in the overlap region (11a).

Among the plurality of solar cells, the second electrode 15 located on the second surface of the adjacent first solar cell 10a and the first electrode 13 located on the first surface of the second solar cell 10b are located in the overlap region 100. They are electrically and physically directly connected by the provided conductive adhesive 501 .

At this time, the first electrodes 13 are physically separated and parallel to adjacent ones in the second direction, but are physically and electrically connected to each other by the conductive adhesive 501 provided in the overlap region 100 . can be connected. Thereby, even if the first electrode 13 does not include a pad or a bus electrode, it is possible to secure a sufficient bonding area with the second electrode 15 of the first solar cell 10a.

Also, as an example, when it is assumed that the second electrode 15 of the first solar cell 10a is formed so as to be physically separated and parallel to the adjacent ones in the second direction, similar to the first electrode 13, the overlapping Even if the first electrode 13 and the second electrode 15 are arranged at different positions in the region 100 , they can be electrically connected by the conductive adhesive 501 . Accordingly, the manufacturing process can be simplified by omitting the alignment process for aligning the first solar cell 10a and the second solar cell 10b.

In one preferred form, the conductive adhesive 501 is preferably provided over the entire overlapping area 100, and the conductive adhesive 501 could be in sufficient contact with the joint 13a of the first electrode 13. It is desirable that the thickness of the conductive adhesive 501 is greater than the thickness of the first electrode 13 .

When the first solar cell 10a is stacked on the second solar cell 10b, in one desirable form, the first solar cell 10a is arranged such that the junction 13a of the second solar cell 10b arranged in the junction region 100 is not visible from the front. It is desirable to be located in

In consideration of this point, the maximum length of the junction 13a (x-axis direction) is substantially the same as the overlapping width of the first solar cell 10a and the second solar cell 10b.

When the first solar cell 10a and the second solar cell 10b are positioned in this manner, a sufficient bonding area is ensured between the second electrode 15 of the first solar cell 10a and the bonding portion 13a located opposite thereto. In addition, since the junction 13a cannot be seen from the front, the design of the solar cell module can be improved.

In a preferred form, the width of the overlapping region 100 along the first direction (the x-axis direction in the figure) is 1-2 (mm). If the width of the overlapping area 100 is less than 1 (mm), the amount of the conductive adhesive applied to the overlapping area 100 is small, making it difficult to obtain sufficient bonding strength. If it is made larger than 2 (mm), the overlapping area 100 reduces the light receiving surface too much, making it difficult to generate the desired solar cell output.

A manufacturing method according to an embodiment of the present invention is a second solar cell 10b having a plurality of first electrodes 13 formed at one end thereof with a joint portion 13a and arranged parallel to each other in a second direction on a first surface of the second solar cell 10b. providing a conductive adhesive 501 to the second solar cell 10b provided with the conductive adhesive 501 (S13); curing the adhesive 501 to physically and electrically connect the first solar cell 10a and the second solar cell 10b (S15).

At this time, as described above, the joint portion 13a is arranged in the overlapping region 100 where the first solar cell 10a and the second solar cell 10b are overlapped, and the conductive adhesive 501 is applied from the overlapping region 100 to the first solar cell 10b. A joint portion 13a of the electrode 13 may be provided to connect with another joint portion adjacent in the second direction.

In step S11, the conductive adhesive 501 can be applied on the second solar cell 10b by a well-known method such as a dispensing method. More preferably, the conductive adhesive 501 is applied onto the front surface of the second solar cell 10b via a dispensing device. It is desirable to supply enough to cover 13a.

Optionally, the conductive adhesive 501 can also be applied to the bonding area 100 of the first solar cell 10a or the bonding areas of each of the first and second solar cells.

In step S13, the first solar cell 10a is positioned with the second side facing the second solar cell 10b, and the joint 13a of the second solar cell with the conductive adhesive 501 of the joint region 100 interposed therebetween; The second electrodes of the first solar cells 10a are positioned to face each other.

In step S15, the conductive adhesive may be cured by heat or UV (ultraviolet) as a heat source. While the conductive adhesive is cured, the first solar cell 10a and the second solar cell 10b can be physically joined and electrically connected.

On the other hand, FIG. 19 is a diagram illustrating a mask pattern used when creating a needle-like electrode.

In general, the electrodes 13 are made by screen printing, and paste is used as the material for forming the electrodes. The paste has viscosity and is thermally cured by baking. By the way, if the paste is printed in the same shape as the electrode during the screen printing process, the paste may not be fired in the same shape as it is printed because the paste is thermally deformed during the firing process. In particular, when the electrode has a needle shape as in one embodiment of the present invention, it is more difficult to manufacture the electrode with a needle shape because the deformation of the paste that occurs during the firing process is large.

Considering this point, in the manufacturing method according to one embodiment of the present invention, it is desirable that the mask pattern (SP) used in screen printing has a stepped shape. For example, the mask pattern (SP) may be formed in a tower shape whose width gradually decreases along the length of the electrode 13, as illustrated in FIG.

As a result, there is an empty space between the printed paste and the electrode 13 due to a step, but the paste expands laterally in the firing process to fill this space. It can be formed to have the same hypotenuse.

Here, the number of steps can be adjusted using parameters such as electrode size, paste point and composition, and process temperature.

Although the preferred embodiments of the present invention have been described in detail above, the scope of rights of the present invention is not limited thereto, and the basic concept of the present invention defined in the following claims is Various modifications and improvements made by persons skilled in the art to be utilized also fall within the scope of the present invention.

Claims (11)

a solar cell,
a semiconductor substrate having a short side in a first direction and a first long side in a second direction intersecting the first direction;
a plurality of electrodes disposed on at least one surface of the semiconductor substrate;
a bushing connecting only a portion of two adjacent electrodes of the plurality of electrodes in the second direction;
the plurality of electrodes are spaced apart from each other in the second direction and extend in the first direction;
each of the plurality of electrodes includes a joint portion arranged adjacent to a first long side and a finger portion extending from the joint portion in the first direction;
the bushing is positioned near a second long side opposite the first long side;
the joint portion is arranged closer to the first long side than the second long side;
a first distance between joints adjacent in the second direction is less than a second distance between finger portions adjacent in the second direction;
The solar cell, wherein each of the plurality of electrodes including the joint portion and the finger portion has a needle shape with a line width gradually decreasing in the first direction. 2. The solar cell of claim 1, wherein the junction is located at one end of each electrode near the first long side of the semiconductor substrate. 3. The solar cell according to claim 1, wherein the area formed by said plurality of electrodes is 5% or less of the total area of at least one surface of said semiconductor substrate. The solar cell according to any one of claims 1 to 3, wherein the plurality of electrodes are spaced from the first long side in the first direction by a distance of 200 µm to 300 µm. The number of the plurality of electrodes is 80 to 120,
The solar cell according to any one of claims 1 to 4, wherein the plurality of electrodes are spaced apart from each other by a distance of 1 mm to 2 mm in the second direction. in the second direction, the distance between two adjacent electrodes in the plurality of electrodes decreases along the first direction;
Adjacent joints of the two adjacent electrodes are arranged at positions where the distance between the two adjacent electrodes is minimal in the second direction. solar cells. The solar cell according to any one of claims 1 to 6 , wherein the junction has an aspect ratio (length in the second direction/length in the first direction) of 1/26 to 3/10. 8. The solar cell of claim 7 , wherein the junction further comprises an open pattern exposing a portion of the semiconductor substrate. A solar cell module,
comprising a plurality of solar cells,
each of the plurality of solar cells,
a short side in the first direction;
a first long side in a second direction that intersects with the first direction;
a first electrode located on a first surface of each solar cell;
a second electrode located on a second surface of each solar cell;
an overlap region disposed on the first long side and partially overlapping adjacent solar cells along the first long side;
The plurality of solar cells includes a first solar cell and a second solar cell adjacent to the first solar cell,
The solar cell module further comprises a conductive adhesive,
the conductive adhesive electrically connects the first electrode of the second solar cell to the second electrode of the first solar cell at the overlap region;
the first electrode comprises a plurality of electrodes;
the plurality of electrodes are arranged apart from each other in the second direction;
each of the plurality of electrodes includes a joint portion arranged in the overlapping region and a finger portion extending from the joint portion in the first direction;
a bushing that connects only a portion of two adjacent electrodes among the plurality of electrodes in the second direction;
the bushing is positioned near a second long side opposite the first long side;
the joint portion is arranged closer to the first long side than the second long side;
a first distance between joints adjacent in the second direction is less than a second distance between finger portions adjacent in the second direction;
The solar cell module, wherein each of the plurality of electrodes including the joint portion and the finger portion has a needle shape with a line width that gradually decreases in the first direction. 10. The method of claim 9 , wherein the junction of each of the plurality of electrodes of the first electrode located on the second solar cell is hidden from view by the first solar cell. solar modules. A method for manufacturing a solar cell module,
The solar cell module comprises a first solar cell and a second solar cell,
each solar cell has a short side in a first direction and a long side in a second direction that intersects with the first direction;
applying a conductive adhesive to the second solar cell;
The second solar cell comprises a plurality of electrodes,
placing the first solar cell on top of the second solar cell in the overlap region where the conductive adhesive is applied; and curing the conductive adhesive to attach the second solar cell to the second solar cell. 1 electrically connecting the solar cell;
each of the plurality of electrodes includes a joint portion arranged adjacent to a first long side and a finger portion extending from the joint portion in the first direction;
the junction is located in the overlap region based on the first solar cell on which the second solar cell is superimposed;
the conductive adhesive connects the joint in the overlapping region to an adjacent electrode spaced apart from the joint in the second direction;
a bushing that connects only a portion of two adjacent electrodes among the plurality of electrodes in the second direction;
the bushing is positioned near a second long side opposite the first long side;
the joint portion is arranged closer to the first long side than the second long side;
a first distance between joints adjacent in the second direction is less than a second distance between finger portions adjacent in the second direction;
The method of manufacturing a solar cell module, wherein each of the plurality of electrodes including the joint portion and the finger portion has a needle shape with a line width gradually decreasing in the first direction.

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